Introduction

This tutorial aims to help you understand and implement common patterns for Firebase Security Rules with Authentication. By the end of this tutorial, you will learn how to write Firebase Security Rules that interact with Firebase Authentication.

Prerequisites:
- Some basic knowledge of Firebase
- Understanding of JavaScript

Step-by-Step Guide

Firebase Security Rules help you secure your data by controlling how your data is read and written. Firebase Authentication works hand-in-hand with these rules, providing user authentication and ensuring that only authenticated users can access your data.

Concept: User-based Security

A common pattern for Firebase Security Rules is to allow users to only read and write their own data. This is often used in applications where each user has a private section in the database.

Example:

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read, write: if request.auth != null && request.auth.uid == userId;
    }
  }
}

In this example, the Firestore database is secured so that each user can only read and write to their own data. The request.auth.uid value is the user's unique ID from Firebase Authentication.

Concept: Role-based Security

Another common pattern is role-based security, where different roles have different permissions.

Example:

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /users/{userId} {
      allow read, write: if request.auth != null && request.auth.token.role == 'admin';
    }
  }
}

In this example, only users who have an 'admin' role can read and write data.

Code Examples

Example 1: User-based Security

In this example, we'll allow users to only delete their own posts.

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /posts/{postId} {
      allow delete: if request.auth != null && request.auth.uid == resource.data.userId;
    }
  }
}

In this code snippet, only the user who created the post (as indicated by the userId field in the post document) can delete the post.

Example 2: Role-based Security

In this example, we'll allow only 'admin' users to create, update, or delete posts.

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /posts/{postId} {
      allow create, update, delete: if request.auth != null && request.auth.token.role == 'admin';
    }
  }
}

In this code snippet, only users with the 'admin' role can create, update, or delete posts.

Summary

In this tutorial, we covered how to use Firebase Security Rules with Firebase Authentication for user-based and role-based security. After following this tutorial, you should be able to implement these common patterns in your own Firebase applications.

Next steps for learning include exploring more complex security patterns and learning how to use Firebase Functions to perform server-side operations.

Additional resources:
- Firebase Security Rules Documentation
- Firebase Authentication Documentation

Practice Exercises

1. Write Firebase Security Rules to allow only the owner of a comment to update or delete it.
2. Write Firebase Security Rules to allow only 'editor' users to create or update posts, but not delete them.

Solutions:

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /comments/{commentId} {
      allow update, delete: if request.auth != null && request.auth.uid == resource.data.userId;
    }
  }
}

Explanation: This rule allows only the owner of a comment (the user with the same uid as the userId field in the comment document) to update or delete the comment.

2.

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /posts/{postId} {
      allow create, update: if request.auth != null && request.auth.token.role == 'editor';
      allow delete: if false;
    }
  }
}

Explanation: This rule allows users with the 'editor' role to create or update posts, but nobody can delete posts (allow delete: if false;).